Food safety and types of food contamination (2023)

Whether you own, run or work in a food business or prepare and serve food at home, it is important to understand potential food safety hazards and risks. Food contamination is one such risk. In this resource, we discuss what food contamination is, the different types and sources of contamination, and preventive measures to ensure food safety.

What is food contamination?

Food contamination refers to when something gets into the food that shouldn't be there, making the food unsafe for consumption. Foodborne diseases and their business-killing cousin,foodborne illnesses outbreak, are caused by food contamination.

While there are many food safety hazards that can cause food contamination, most fall into one of three categories: biological, physical, or chemical contamination. In many cases, a single hazard can introduce more than one type of contamination into food.

Types of food contamination.


Biological contamination occurs when food is contaminated with living organisms or the substances they produce. This includes biological material produced by humans, rodents, insects and microorganisms. Biological contamination is the leading cause of foodborne illness and foodborne illness* and a common cause of food spoilage and food waste. they existSix types of microorganisms that can cause foodborne illness: bacteria, viruses, parasites, protozoa, fungi and prions.

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Most foodborne illnesses in Canada are caused by bacteria or viruses, the most common are:

  • Norovirus
  • Listeria
  • salmonella
  • E coli
  • Campylobacter

Foodborne illness occurs when disease-causing microorganisms, also called pathogens, get into food and multiply to unsafe levels before consumption. This can happen remarkably quickly; Under ideal conditions for bacterial growth, a single-celled bacterium can grow to two million in just seven hours.

Bacteria and other pathogens thrive on foods that:

  • Wet
  • High in protein or starch
  • neutral in the acid

Foods that meet these criteria are labeled as potentially hazardous orHigh risk foods🇧🇷 All high-risk foods are teeming with pathogens and other bacteria; It is your responsibility to prevent bacteria from multiplying to unsafe levels and, if possible, destroy them during the cooking process.

To slow bacterial growth and avoid food safety hazards, you must follow food safety best practices designed to control bacterial growth through proper, rigorous food handling and disinfection proceduresjTime and temperature controlfrom eating.

Food poisoning occurs when certain toxins are consumed, such as those produced by salmonella, staph, or listeria. Microbial toxins are extremely powerful toxins that can deactivate the immune system and damage tissues if ingested. Many microbial toxins are heat resistant. Even if the bacteria are destroyed during cooking, the toxins remain in the food and can cause severe symptoms almost immediately.

To minimize the risk of food biofouling in your food business, always do the following:

  • Keep high-risk foods (e.g. meat, poultry, dairy, eggs) out of the temperature danger zone**
  • Buy, store, thaw, prepare, cook and serve high-risk foods properly
  • Regularly clean and disinfect all surfaces and equipment that come into contact with food.
  • Maintain good hygiene and general hygiene of the premises.
  • Maintain high standards of personal hygiene (and ensure all employees do the same)

*The terms “foodborne illness” and “food poisoning” have slightly different meanings, but are often used interchangeably to describe any foodborne illness caused by microorganisms or their derivatives.

**In Manitoba, the temperature hazard zone is 5°C to 60°C (41°F to 140°F). In all other Canadian provinces and territories, the temperature ranges from 4°C to 60°C (40°F to 140°F).

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Physical contamination occurs when a physical object enters the food at some stage in the production or preparation process. Physical objects in food can pose a choking hazard and often introduce biological contaminants as well. While the item is unlikely to harm your customer, finding an item in your food (who knows what harmful microorganisms in the item could make you sick) can be very distressing for a customer.

Common examples of physical contaminants in food companies include:

  • Fur
  • nails
  • restrictions
  • jewelers
  • Broken glass, staples
  • plastic wrap/packaging
  • Dirty, unwashed fruits and vegetables
  • Pests, pest droppings, rodent hair

To minimize the risk of physical contamination of food in your catering business, you should always:

  • Wear your hair neatly tied back or use a hair/beard net
  • Keep jewelry to a minimum
  • If necessary, use brightly colored bandages that are easy to see when they fall off.
  • Discard and replace cracked, chipped or broken cutlery, glassware and utensils
  • Use a plastic or metal spoon for ice (never use the glass!)
  • Wash fruits and vegetables well
  • Establish pest prevention and control procedures as part of your food safety plan


Chemical contamination occurs when food produces or comes into contact with toxic chemicals, which can lead to chemical food poisoning. Chemical pollutants fall into one of two categories: natural and artificial.

Common chemical contaminants include:

  • Cleaning agents (e.g. cleaning agents, disinfectants)
  • Pesticides/Herbicides
  • Toxic chemicals in metals and plastics
  • preservatives
  • natural toxins

Naturally occurring toxins are toxic compounds produced by living organisms, some of which are staples of the human diet (eg, shellfish, potatoes, fish). These toxins are not harmful to the organisms themselves, but they can harm us if we eat them.

Minimal contamination with natural toxins cannot cause disease, but food processors should be aware of thiswhich foods produce toxinsand take all reasonable precautions to ensure food is safe for consumption. Potatoes, for example, produce glycoalkaloids that are toxic to humans. Most of these toxins are found in or just under the skin and in the eyes or potato sprouts. Green skin can indicate the presence of toxins, so be sure to remove any green eyes, sprouts, or skin if you decide to use potatoes that have turned green or have sprouted.

There are many ways that food in a commercial kitchen can become contaminated with artificial/synthetic chemicals. Food processors can inadvertently cause chemical contamination when:

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  • Do not store cleaning supplies and other chemicals properly.
  • Use plenty of detergent or disinfectant to clean kitchen surfaces, glasses, plates or cutlery (observe manufacturer's instructions!)
  • Not rinsing surfaces, glasses, plates or cutlery properly after cleaning and disinfecting (if applicable).
  • Not washing fruits and vegetables properly to remove pesticides.
  • Use of cookware or containers made of materials that are not food safe or not intended for reuse (use only food safe plastics and metals)
  • Using pest control agents (e.g. spray, poison bait) incorrectly

To minimize the risk of chemical contamination in your grocery store, always do the following:

  • Label and store chemicals separately from food.
  • Use the chemical appropriate for your job.
  • Follow the chemical manufacturer's instructions for dilution, exposure time, and water temperature.
  • Use pest control chemicals with extreme care or outsource pest control to a professional pest control service.


Cross-contamination is the accidental transfer of contaminants from one surface or substance to another, usually as a result of improper handling procedures. In a food environment, the term refers to the transfer of contaminants from a surface, object or person to food. Cross contamination usually refers to biological contamination but can also be physical or chemical.

Cross-contamination in a food business often occurs as a result of:

  • Handling food (e.g. microorganisms from sweat, sneezing/coughing, hands, hair, clothing)
  • Improper food handling (eg, reusing cutting boards or utensils for raw and cooked food, or for different types of food)
  • Inadequate cleaning and hygiene (e.g., failure to properly rinse cleaning chemicals from prep surfaces, dishes, glassware, or appliances)
  • Improper food storage (eg, storing raw meat on shelves above ready-to-eat food)
  • Improper waste disposal (e.g., overflowing trash cans)
  • pests

Cross-contamination can also pose a risk to customers with food allergies, as traces of an allergen can be transmitted as well as microorganisms. Even small amounts of an allergen can cause a serious allergic reaction, in some cases a fatal reaction. As a food business owner, manager or employee, it is your responsibility to serve a safe meal to customers, including those with food allergies.

To minimize the risk of cross-contamination in your grocery store, always:

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  • Move in the company according to thefood safety plan(e.g. changing dirty kitchen linens before moving from the raw to the finishing station)
  • Cover raw foods and store on shelves under cooked or ready-to-eat foods in the refrigerator (read more aboutProtection against contamination in the refrigerator)
  • Use separate appliances or utensils to prepare raw and cooked food
  • Use separate appliances or utensils to cook different types of food
  • Prepare allergen-free meals separately
  • FoundAllergen Management Proceduresas part of your food safety plan
  • Maintain high standards of personal hygiene.
  • Wash your hands frequently with theproper hand washing technique
  • Handle and dispose of leftover food and waste properly (e.g. ensure containers are sealed and stored away from food)

Pests deserve special mention in this context, as they are a notorious source of cross-contamination in food companies. Rodents, flies and cockroaches carry countless disease-causing bacteria and other pathogens on their bodies, in their feces, urine and saliva, including salmonella, E. coli and listeria.

Therefore, pest prevention and control in the workplace is vital. Download theCIFS Guide to Pest Prevention and Controlfor more information on the risks common pests pose to a food business, how to prevent pests from entering your business and what to do if they do.

Related Resources:

Cross-contamination in commercial kitchens

Getting to the heart of the truth about cutting board hygiene

The best way to prevent food contamination in your business

The above food safety best practices are by no means a comprehensive list of everything you should do to prevent food contamination and its consequences in the food business you own, manage or operate.

Everyone working in the food industry has a legal obligation to take all reasonable steps to protect the public they serve from health risks such as foodborne illness and food allergies. You should too, because your income is directly linked to the success of the company.

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The best way to prevent food contamination and ensure food safety is through education and training.Fully trained grocersThey know what they need to do to control food safety risks and understand that taking shortcuts when it comes to food safety has consequences for everyone.

ÖCanadian Institute for Food Safety (CIFS)provides online training, education and resources to thousands of Canadian food workers as part of our mission to reduce foodborne illness and other food safety risks in Canada.


What are the 4 types of food safety contamination? ›

There are four types of hazards that you need to consider:
  • Microbiological hazards. Microbiological hazards include bacteria, yeasts, moulds and viruses.
  • Chemical hazards. ...
  • Physical hazards. ...
  • Allergens.
Oct 19, 2016

What are the types of food contamination explain briefly each type? ›

There are four main types of contamination: chemical, microbial, physical, and allergenic. All food is at risk of contamination from these four types. This is why food handlers have a legal responsibility to ensure that the food they prepare is free from these contaminants and safe for the consumer.

What is the main cause of food contamination answer? ›

Unwashed knives, cutting boards or other kitchen tools can spread contaminants. Improper storage. Food left out for too long at room temperature can become contaminated. Food stored in the refrigerator for too long can spoil.

How can you prevent food contamination when handling food list any five 5 ways? ›

use clean equipment, rather than hands, to pick up food. wear clean clothes or a clean apron. wash fruit and vegetables to be eaten raw under running water. cook food thoroughly, especially minced meat, burger patties, sausages, rolled roasts, stuffed meats, rabbit, seafood, poultry and eggs.

What are 5 ways food can be contaminated? ›

Avoid these 5 things: Most common ways food is contaminated in a restaurant
  • Temperature abuse. ...
  • Cross-contamination. ...
  • Unsafe ingredients. ...
  • Improper storage conditions. ...
  • Shipping damage.
Jul 20, 2017

What are the 3 main types of contamination? ›

While there are many food safety hazards that can cause food contamination, most fall into one of three categories: biological, physical or chemical contamination. In many cases, a single hazard can introduce more than one type of contamination to food.

What is the most common type of food contamination? ›

Bacterial contamination is thought to be the most common cause of food poisoning worldwide, and the best way to protect against it occurring is by maintaining the best food safety practices. Physical contamination refers to food that has been contaminated by a foreign object at some stage of the production process.

How can we prevent food contamination? ›

4 Steps to Prevent Food Poisoning
  1. Clean. Wash your hands and work surfaces before, during, and after preparing food. ...
  2. Separate. Separate raw meat, poultry, seafood, and eggs from ready-to-eat foods. ...
  3. Cook. Cook food to the right internal temperature to kill harmful bacteria. ...
  4. Chill. Keep your refrigerator 40°F or below.
Feb 22, 2022

What is the most common method of contamination? ›

Hands to food: Usually germs are transmitted from unclean hands to food by an infected food preparer who didn't wash his or her hands after using the toilet. The germs are then passed to those who eat the food. This is easily prevented by always washing your hands after using the toilet and before preparing food items.

What is food contamination short answer? ›

Food contamination is generally defined as foods that are spoiled or tainted because they either contain microorganisms, such as bacteria or parasites, or toxic substances that make them unfit for consumption.

How does contamination happen? ›

Biological contamination

The problem occurs when bacteria or other harmful microorganisms get into food. They are a common cause of food poisoning, spoilage and costly waste. Biological hazards include microorganisms such as bacteria, viruses, yeasts, moulds and parasites.

How does most contamination happen? ›

Majority of the food contamination occurs through naturally occurring toxins and environmental pollutants or during the processing, packaging, preparing, storage, and transportation of food.

What are the 7 important things to keep food safe? ›

  • Keep high-risk food at 5 °C or below or above 60 °C to avoid the temperature danger zone and food poisoning.
  • Store raw foods below cooked foods.
  • Store food in suitable, covered containers.
  • Avoid refreezing thawed foods.
  • Check and observe the use-by dates on food products.
  • Take special care with high-risk foods.

Why is it important to protect food contamination? ›

Contamination of food from objects, people, pests or chemicals can cause serious illness. Food businesses, by law, must take precautions to avoid causing harm to people who eat their food.

What are 3 ways food handlers can contaminate food? ›

Food handlers can contaminate food when they:

Have wounds that contain a pathogen. Sneeze or cough. Have contact with a person who is sick. Touch anything that may contaminate their hands and do not wash them.

What are the three main causes of food contamination? ›

There are three ways that food can be contaminated:
  • biological hazards (microorganisms) including bacteria, fungi, yeasts, mould and viruses.
  • chemical hazards. including cleaning chemicals or foods with naturally occurring toxins, such as green potatoes.
  • physical hazards.

What are the 6 most common sources of contamination? ›

The most common objects to contaminate food include glass, hair, metal, jewellery, dirt, and fingernails.

What are the 3 main ways to avoid cross contamination? ›

To prevent this: Wash hands with soap and hot water before and after handling food, and after using the bathroom, changing diapers; or handling pets. Use hot, soapy water and paper towels or clean cloths to wipe up kitchen surfaces or spills. Wash cloths often in the hot cycle of your washing machine.

What are the 4 main causes of food poisoning or contamination? ›

Causes of food poisoning
  • not cooking food thoroughly (particularly meat)
  • not correctly storing food that needs to be chilled at below 5C.
  • keeping cooked food unrefrigerated for a long period.
  • eating food that has been touched by someone who is ill or has been in contact with someone with diarrhoea and vomiting.

What is direct contamination in food? ›

Direct contamination occurs when raw food or the plants and animals from which they come, in their natural setting or habitat, are contaminated by chemical or biological contaminants that are present in the air, soil or water.

What is an example of contamination? ›

Examples of Contamination in Processing

During the slaughter process, germs on an animal's hide that came from the intestines can get into the final meat product. If germs contaminate surfaces used for food processing, such as a processing line or storage bins, germs can spread to foods that touch those surfaces.

What is the best example of contamination? ›

Examples of Physical Contamination

Common examples of physical contaminants include hair, bandages, fingernails, jewelry, broken glass, metal, paint flakes, bone, the body parts of pests, or pest droppings.

Who is most at risk of contamination food? ›

These groups of people are:
  • Adults Aged 65 and Older. ...
  • Children Younger Than 5 Years. ...
  • People with Weakened Immune Systems. ...
  • Pregnant women are more likely than other people to get sick from certain germs.

What are common sources of contamination? ›

Pesticides present in fruits and vegetables are one of the main sources of contamination. In addition, kitchen cleaning agents, food containers made of non-safe plastic, pest control products also lead to food contamination.

What is basic food safety? ›

Four Steps to Food Safety: Clean, Separate, Cook, Chill. Four Steps to Food Safety. Español (Spanish) Following four simple steps at home—Clean, Separate, Cook, and Chill—can help protect you and your loved ones from food poisoning.

What is the importance of keeping food clean and safe? ›

It is important that the food we eat and the water we drink is clean and safe. So it is essential to prepare meals in a safe, hygienic way. If germs (such as harmful micro-organisms and parasites) get into our foods and drinks, they may give us food poisoning (resulting, for example, in diarrhoea or vomiting).

What is the difference between food contamination and food poisoning? ›

Food poisoning, or foodborne illness, occurs when you eat contaminated food. Contaminated means it's infected with a toxic organism, such as a bacteria, fungus, parasite or virus. Sometimes the toxic byproducts of these organisms cause food poisoning.

How do you identify contamination? ›

Bacterial contamination is easily detected by visual inspection of the culture within a few days of it becoming infected;
  1. Infected cultures usually appear cloudy (i.e., turbid), sometimes with a thin film on the surface.
  2. Sudden drops in the pH of the culture medium is also frequently encountered.

What temperature kills bacteria in food? ›

It is a myth that bacteria are killed at temperatures below 40 degrees. In fact, bacteria growth is slowed, but not stopped. The only way to kill bacteria by temperature is by cooking food at temperatures of 165 degrees or more. Bacteria also die in highly acidic environments like pickle juice.

What are examples of contaminated food? ›

Raw foods of animal origin are the most likely to be contaminated, specifically raw or undercooked meat and poultry, raw or lightly cooked eggs, unpasteurized (raw) milk, and raw shellfish. Fruits and vegetables also may get contaminated.

What are the 4 biological contamination? ›

The most common examples of biological contamination include bacteria, viruses, parasites, and fungi.

What are 4 ways to prevent cross contamination? ›

Preparing food hygienically
  1. use different utensils, plates and chopping boards for raw and cooked food.
  2. wash utensils, plates and chopping boards for raw and cooked food thoroughly between tasks.
  3. make sure you do not wash raw meat.
  4. wash your hands after touching raw food and before you handle ready-to-eat food.

What are the 4 things that must be done if cross contamination is discovered? ›

These include:
  • Use separate equipment for raw and ready-to-eat food. ...
  • Properly clean and sanitize before and after tasks. ...
  • Prep raw and ready-to-eat-food at separate times. ...
  • Buy food that's already been prepared.
Jun 8, 2021

What are the 4 types of food spoilage? ›

8.5 Food spoilage
  • 1 Microbial spoilage. Microbial spoilage is caused by microorganisms like fungi (moulds, yeasts) and bacteria. ...
  • 2 Physical spoilage. Physical spoilage is due to physical damage to food during harvesting, processing or distribution. ...
  • 3 Chemical spoilage. ...
  • 4 Appearance of spoiled food.

What is the most common type of contamination? ›

Bacterial contamination is thought to be the most common cause of food poisoning worldwide, and the best way to protect against it occurring is by maintaining the best food safety practices. Physical contamination refers to food that has been contaminated by a foreign object at some stage of the production process.

What is an example of physical contamination in food? ›

Because of the obvious risk of injury they present, each one is dangerous if left undetected. The most common examples of physical food contaminants include metal, glass, plastic, rubber, wood, stone and bone.

What are 10 ways to prevent food contamination? ›

10 ways to prevent food poisoning
  • Wash your hands. ...
  • Wash worktops. ...
  • Wash dishcloths. ...
  • Use separate chopping boards. ...
  • Keep raw meat separate. ...
  • Store raw meat on the bottom shelf. ...
  • Cook food thoroughly. ...
  • Keep your fridge below 5C.

What are solutions to food contamination? ›

Wash hands before touching the food. Prevent cross-contamination by surfaces and containers. Separate cooked foods from raw foods. Use boiling water, especially if the food will not undergo additionally cooking.

What temperature is hot holding? ›

Hot food must be kept at 63°C or above, except for certain exceptions. When you display hot food, e.g. on a buffet, you should use suitable hot holding equipment to keep it above 63°C.

How do you prevent contamination? ›

Keep it clean:

Wash hands with soap and hot water before and after handling food, and after using the bathroom, changing diapers; or handling pets. Use hot, soapy water and paper towels or clean cloths to wipe up kitchen surfaces or spills. Wash cloths often in the hot cycle of your washing machine.

What temperature is food danger zone? ›

The temperature danger zone is between 41°F and 135°F. TCS food must pass through the temperature danger zone as quickly as possible. Keep hot food hot and cold food cold.

What are the 6 ways to prevent cross contamination? ›

Think about these 6 things to keep things clean and safe.
  • Mind Your Cutting Boards. Every kitchen should have at least two cutting boards (at least!) ...
  • Wash Your Hands! The signs in restaurants say this for a reason. ...
  • Watch the Juices. ...
  • Don't Rinse Meats. ...
  • Properly Rinse Produce. ...
  • Clean All Surfaces.

What are the main types of food contamination hazards? ›

There are four types of food contamination: physical, biological, chemical and allergenic.

What are the effects of food contamination? ›

Bacteria. Salmonella, Campylobacter and enterohaemorrhagic Escherichia coli are some of the most common foodborne pathogens that affect millions of people annually, sometimes with severe and fatal outcomes. Symptoms can be fever, headache, nausea, vomiting, abdominal pain and diarrhoea.

What is the best example of physical contamination? ›

Examples of Physical Contamination

Common examples of physical contaminants include hair, bandages, fingernails, jewelry, broken glass, metal, paint flakes, bone, the body parts of pests, or pest droppings.


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